Helium atom scattering technique

To conclude, it seems that the nature of the anharmonic coupling between a high frequency intramolecular mode and a thermally excited low frequency mode is understood. It turns out that the strength of the influence on the infrared spectrum critically depends on the values of (Oq, Sm and t. However, we have to wait for more experimental data on these low frequency modes, probably obtained with the helium atom scattering technique, bdbre we can make more definite conclusions. 

In the fields of solid-state and molecular physics, there have been many different experimental techniques introduced for vibrational spectroscopy. However, the investigation of the vibrational properties of bare solid surfaces is dominated by the two techniques of helium atom scattering (HAS) and high-resolution electron energy loss spectroscopy (HREELS). Both have been used to map surface phonon dispersions. In addition, that is, optical techniques such as infrared absorption spectroscopy (IRAS) (Chapter 3.4.1) and recentiy also inelastic tunneling... 

Other techniques used in surface structure determination include extended X-ray absorption fine structure (EXAFS), ion scattering, electron forward focusing, and helium atom diffraction. 

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